Theatrical, television, touring productions, and architectural lighting sources often include lighting devices that emit a light beam with different divergences. The light beam divergence is used to obtain a particular desired artistic objective. The artistic requirements may require that the beam divergence remain static or that it change over time. Cost, speed of changing, smoothness of changing, compact size, weight, and efficiency of transmitting light are all factors in the practical usage of a beam divergence module. Further, changing the shape of the projected beam from round to oval is a desired attribute of a beam divergence module. The changing of shape is required to create a circular spot when the light is projected on a surface that is not perpendicular to the beam.
In the past, the divergence of a light source was changed by manually replacing the light source type to obtain a specific artistic result. The use of a specific lamp for each type of divergence sought makes it impractical to change the divergence of the light source during a performance. Therefore more overall lighting fixtures are required to accomplish the desired artistic results.
To change the orientation of an oval shaped beam one would need to manually change the radial orientation of the light source.
Accordingly, inventors have created several methods to remotely change the divergence of a light beam. U.S. Pat. No. 4,855,884, issued Aug. 8, 1989, to the present inventor Richardson, discloses an improved reflector that changes beam divergence. This invention is limited in that it does not allow for the changing of the shape of the beam and is limited in the range of size produced.
U.S. Pat. No. 4,973,306, issued Nov. 20, 1990, to Bornhorst, discloses a series of diffusion panels that are introduced from the sides of a beam of light. This creates various beam divergences, however, this fails to create a range of beams with a smooth field of illumination. Further, this system comprises a complex mechanism that is costly and unreliable. It also provides no method to change beam shape.
U.S. Pat. No. 5,073,847, also to Bornhorst, discloses another diffusion mechanism. A series of rotatable diffusion panels are arranged in a radial array. Rotation of the panels into the light path diffuse the light beam. This mechanism also proves to be expensive and provides no method to shape the beam. There is also an insufficient range of beam sizes to provide a smooth transition from narrow to full diffusion.
U.S. Pat. No. 5,665,305, issued Sep. 9, 1997, to Belliveau, et al., discloses a method of intervening one or two lenticular panels to change beam divergence and or beam shape. These panels are oriented so as to be orthogonal to one another when engaged. This method does not allow for continuous changes in beam size or shape.
Accordingly, it is an object of the present invention to provide a light beam divergence and shaping module that is compact, and that is inexpensive to produce and to maintain. The module is of simple construction, and is therefore very reliable.
It is a further object of the present invention to provide a module that provides a wide range of beam divergence, and that changes from one divergence to another quickly and smoothly.
It is a still further object of the present invention to provide a device that efficiently transmits light.